Modular, adaptable holders for sensors and battery cells for physical analysis

ABSTRACT

Systems and methods for battery testing including a holder system. The holder system is designed to couple one or more transducers to a battery under test, wherein the one or more transducers are configured for electrochemical-acoustic signal interrogation (EASI) of the battery. The holder system includes at least one arm to house at least one transducer to be coupled to the battery, and a pressure applying device to apply pressure to the at least one transducer, and to control pressure between the at least one transducer and the battery. The holder system is also configured to determine the pressure between the at least one transducer and the battery and adjust the pressure applied to the at least one transducer based on the determined pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application for Patent claims the benefit of ProvisionalPatent Application No. 62/416,497 entitled “MODULAR, ADAPTABLE HOLDERSFOR SENSORS AND BATTERY CELLS FOR PHYSICAL ANALYSIS” filed Nov. 2, 2016,pending, and assigned to the assignee hereof and hereby expresslyincorporated herein by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with U.S. Federal Government support under GrantNo. SBIR 1621926 awarded by the National Science Foundation. The U.S.Federal Government has certain rights in the invention.

FIELD OF DISCLOSURE

Disclosed aspects are directed to battery diagnostics. Morespecifically, exemplary aspects are directed to modular, adaptableholders configured to accommodate one or more types of sensors for usein physical analysis of one or more types and/or shapes of batteries.

BACKGROUND

The battery industry currently lacks techniques which have attributes ofbeing scalable, consistent, non-destructive, stand-alone, etc., fordetecting physical characteristics and changes thereof in a batteryduring manufacturing or in use. Some conventional techniques for batterydiagnostics involve measuring physical characteristics of batteries suchas temperature, internal pressure, stress-strain, open circuit voltage,direct current (DC) impedance, alternating current (AC) impedance, andcurrent-voltage characteristics.

Information gathered about a battery using the above techniques can beused to infer different aspects of the overall condition of the battery.For example, an increase in temperature in a Lithium-ion (Li-ion)battery during charge-discharge cycling of the Li-ion battery canindicate the charge-discharge rate or power output of the Li-ionbattery. Alternatively, the increase in temperature can indicatepotential formation of internal short circuits or breakdown ofelectrolytes in the Li-ion battery. In another example, a strain gaugeplaced at a surface of a pouch cell type battery can be used to detect abuildup of pressure within the pouch cell (e.g., due to formation of gaswithin the pouch cell); or to detect a degradation state of electrodeswithin the pouch cell.

Electrochemical-acoustic signal interrogation (EASI) is anotherdiagnostic technique that uses ultrasound signals to measure changes inthe physical properties of batteries. EASI operates on the principlethat the acoustic behavior of a battery is sensitive to any change inphysical properties along a path travelled by sound waves of theultrasound signals. Accordingly, EASI may be used to directly andactively probe internal components of the battery (wherein, it will berecognized that electrical, thermal, and strain-based diagnostictechniques are not capable of such probing as is made possible by EASI).In addition, EASI is also agnostic to chemistries or geometries ofbatteries. EASI may also be implemented with minimal hardware, such as apair of transducers in direct contact with the body of the battery.

With reference to FIG. 1, a schematic of system 100 comprising examplehardware for EASI is shown. System 100 comprises battery 102, to which apair of transducers 108 a-b may be affixed on two locations (e.g., onopposite sides) on the surface of battery 102. Hardware such as screws106 a-b are shown, but other alternative means for affixing transducers108 a-b to the body of battery 102 may be used. Battery cycler 110represents a controller for charging-discharging battery 102 and may beconnected to battery 102 through terminals 104 a-b of battery 102.Ultrasonic pulser/receiver 112 is coupled to transducers 108 a-b,wherein through the control of one of ultrasonic pulser/receiver 112,one of transducers 108 a-b is configured to transmit ultrasonic signalswhile the other one of transducers 108 a-b is configured to receive thetransmitted ultrasonic signals. A computer (not separately shown) whichmay be provided within or coupled to the block identified as ultrasonicpulser/receiver 112 may be configured to analyze the received ultrasonicsignals and infer the characteristics of battery 102 according to EASItechniques.

Although a wide variety of physical sensors may be employed by a EASIsystem such as system 100, it is observed that a single sensor type maynot be able to detect all aspects of the physical characteristics andchanges thereof that may determine a battery's condition. Hence, somebattery diagnostic approaches may employ two or more measurementtechniques using different sensor types to obtain a more completepicture of the condition of the batteries, especially while thebatteries are in use. However, with the exception of electrical testingmethods, in which the electrical leads are connected to the tabs of thebatteries there is no standard method in the art for maintainingphysical contact between the measurement sensors, particularly EASIsensors such as transducers 108 a-b and the surface of the battery'sbody.

There is accordingly a need for modular, adaptable holders that can beused for different types of batteries (e.g., cylindrical batteries,pouch type cells, etc.) which are compatible with and can accommodatemultiple types of measurement sensors.

SUMMARY

Exemplary aspects of this disclosure are directed to systems and methodsfor battery testing. A holder system is designed to couple one or moretransducers to a battery under test, wherein the one or more transducersare configured for electrochemical-acoustic signal interrogation (EASI)of the battery. The holder system includes at least one arm to house atleast one transducer to be coupled to the battery, and a pressureapplying device to apply pressure to the at least one transducer, and tocontrol pressure between the at least one transducer and the battery.The holder system is also configured to determine the pressure betweenthe at least one transducer and the battery and adjust the pressureapplied to the at least one transducer based on the determined pressure.

For example, an exemplary aspect is directed to an apparatus comprisinga holder system. The holder system is configured to couple one or moretransducers to a battery, the one or more transducers configured forelectrochemical-acoustic signal interrogation (EASI) of the battery. Theholder system comprises at least one arm configured to house at leastone transducer to be coupled to the battery, and a pressure applyingdevice configured to apply pressure to the at least one transducer, tocontrol pressure between the at least one transducer and the battery.

Another exemplary aspect is directed to a method of testing a battery.The method comprises coupling one or more transducers to the battery,the one or more transducers configured for electrochemical-acousticsignal interrogation (EASI) of the battery and coupling the at least onearm to the battery, wherein at least one transducer is housed in the atleast one arm. The method further comprises applying pressure to the atleast one transducer, to control pressure between the at least onetransducer and the battery.

Yet another exemplary aspect is directed to a battery holder systemcomprising means for housing at least one transducer to be coupled to abattery under test, the at least one transducers configured forelectrochemical-acoustic signal interrogation (EASI) of the battery, andmeans for applying pressure to the at least one transducer forcontrolling pressure between the at least one transducer and thebattery.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofvarious aspects of the invention and are provided solely forillustration and not limitation.

FIG. 1 is a schematic that illustrates example hardware for EASI.

FIGS. 2A-D illustrate example holder systems for EASI of batteriesaccording to exemplary aspects of this disclosure.

FIGS. 3A-E illustrate example mechanisms for applying and adjustingpressure between transducers and batteries under test, according toaspects of this disclosure.

FIG. 4 illustrates an example holder system with a gravity-assistedmechanism for applying pressure between transducers and batteries undertest, according to aspects of this disclosure.

FIG. 5 illustrates an example automation process for battery testing,according to aspects of this disclosure.

FIG. 6 illustrates example aspects of couplants used in improvingmechanical contact between transducers and batteries, according toexample aspects of this disclosure.

FIG. 7 illustrates aspects of a waveguide configured to position thebattery at a distance beyond a near field of a transducer, according toexample aspects of this disclosure.

FIG. 8 illustrates a method of testing a battery using a holder system,according to example aspects of this disclosure.

DETAILED DESCRIPTION

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific aspects of the invention.Alternate aspects may be devised without departing from the scope of theinvention. Additionally, well-known elements of the invention will notbe described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any aspect described herein as “exemplary”is not necessarily to be construed as preferred or advantageous overother aspects. Likewise, the term “aspects of the invention” does notrequire that all aspects of the invention include the discussed feature,advantage or mode of operation.

The terminology used herein is for the purpose of describing particularaspects only and is not intended to be limiting of aspects of theinvention. As used herein, the singular forms “a,” “an,” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises”, “comprising,” “includes,” and/or “including,” when usedherein, specify the presence of stated features, integers, steps,operations, elements, and/or components, but do not preclude thepresence or addition of one or more other features, integers, steps,operations, elements, components, and/or groups thereof.

Further, many aspects are described in terms of sequences of actions tobe performed by, for example, elements of a computing device. It will berecognized that various actions described herein can be performed byspecific circuits (e.g., application specific integrated circuits(ASICs)), by program instructions being executed by one or moreprocessors, or by a combination of both. Additionally, these sequence ofactions described herein can be considered to be embodied entirelywithin any form of computer-readable storage medium having storedtherein a corresponding set of computer instructions that upon executionwould cause an associated processor to perform the functionalitydescribed herein. Thus, the various aspects of the invention may beembodied in a number of different forms, all of which have beencontemplated to be within the scope of the claimed subject matter. Inaddition, for each of the aspects described herein, the correspondingform of any such aspects may be described herein as, for example, “logicconfigured to” perform the described action.

Exemplary aspects of this disclosure are directed to holders configuredto enable attachment of one or more sensors, which may be of differenttypes, to batteries of different types and/or geometries, the one ormore sensors for aiding diagnostics of the batteries. It will beunderstood that references to “batteries” in this disclosure do notassume any inherent limitation as to any specific type of battery orcell but are generally meant to cover any type of electrochemical energystorage device.

With reference to FIGS. 2A-D, schematic views of exemplary holdersystems 200, 220, 240, and 260 are illustrated therein. Holder systems200, 220, 240, and 260 generally comprise one or more sensors, or moregenerally, one or more transducer units configured to be mechanicallycoupled (e.g., affixed or attached) to different types of batterieswhich may be of different geometries.

For example, starting with FIG. 2A, top and side views of holder system200 are shown. Holder system 200 comprises battery 202, which may be apouch/prismatic cell. Two representative portions of holder system 200,generally referred to as “arms” are shown and designated with referencenumerals 204 a-b. Arms 204 a-b may be movable and configured toestablish contact with various surfaces of battery 202. Arms 204 a-bcomprise transducers 208 a-b, respectively, wherein each one oftransducers 208 a-b is configured to transmit and/or receive acousticsignals such as ultrasonic sound signals into/from battery 202. Althoughtwo transducers 208 a-b are illustrated, wherein one of the twotransducers 208 a-b may be configured to transmit the acoustic signalsand the other one of the two transducers 208 a-b may be configured toreceive the transmitted, signals, it will be understood that a singletransducer may also be configured to both transmit and receive (e.g.,reflected signals) for the purposes of physical analysis of battery 202.

Although not explicitly shown, there may be various control mechanismsfor directing transducers 208 a-b, processing mechanisms for analyzingthe acoustic signals for diagnosing battery 202, etc., configured tocooperate with holder system 200. In one aspect, arms 204 a-b may beconfigured to place transducers 208 a-b coaxially on opposite sides ofbattery 202. Transducers 208 a-b need not be aligned to maintain anytype of symmetry (e.g., in a transverse direction in either the top viewor the side view), and their respective alignment may be based on thetype of analysis desired. Arms 204 a-b of holder system 200 may alsocomprise slots to accommodate battery 202 of different geometries, andcorrespondingly, slots for transducers 208 a-b to be aligned at adesired angle with respect to, e.g., perpendicular to, the surface ofbattery 202. As previously mentioned, arms 204 a-b may be individuallyand independently moveable for obtaining acoustic signal based analysis(e.g., EASI) at different positions along the surface of battery 202.The movement, alignment, and/or actuation of arms 204 a-b may beachieved by robotic or computer-controlled mechanisms in exemplaryaspects.

It is recognized that the pressure applied to transducers 208 a-b attheir area of contact with battery 202 may affect the measurements ofsignals transmitted/received through battery 202. Therefore, it isdesirable to control the pressure applied to the one or more transducerssuch as 208 a-b. Accordingly, in one aspect, a pressure applying deviceor means for applying pressure, such as, springs, pneumatic pressuremechanisms, lead screws, linear actuators, electromagnetic solenoids,linear motor actuators, hydraulic mechanisms, etc., for applying andmaintaining consistent and preferably adjustable pressure may beprovided in arms 204 a-b, respectively. FIG. 2A illustrates an exemplaryaspect wherein such means for applying pressure include springs 206 a-b,while FIG. 2D illustrates other means for applying pressure. As shown,springs 206 a-b may be configured to apply pressure on transducers 208a-b to control their mechanical coupling to the surface of battery 202(wherein in the illustrated example, each of transducers 208 a-b isshown as being disposed in between respective one of springs 206 a-b andbattery 202). Using springs 206 a-b configured as identical precisioncompression springs, for example, equal stack pressure may be applied toboth transducers 208 a-b. By adjusting spring compression distance withspring stiffness for springs 206 a-b, the pressure at the interfacesbetween transducers 208 a-b and respective surfaces of battery 202, canbe adjusted, e.g., tuned from 1 to 10 pounds per square inch (psi)(while other actuation methods, e.g., as will be further described withreference to FIG. 2D may be used to control the pressure from 1 to 50psi or more).

FIG. 2B shows top and side views of holder system 220, which may besimilar in some aspects to holder system 200 described above.Accordingly, like components of holder system 220 may be configured insimilar fashion as holder system 200 of FIG. 2A and a repetition of thedescription of like components will be avoided for the sake of brevity.Notably, holder system 220 may be configured to mechanically orphysically couple arms 224 a-b comprising transducers 228 a-b to battery222 for the purposes of physical analysis of battery 222, e.g., usingEASI. Battery 222 may be a cylindrical cell and arms 224 a-b may becorrespondingly configured to accommodate the cylindrical geometry ofbattery 222. Arms 224 a-b may also comprise means for applying pressuresuch as springs 226 a-b coupled to transducers 228 a-b, respectively.

FIG. 2C shows another exemplary holder system 240 configured toaccommodate more than two transducer units for use in EASI, for example.Specifically shown in the top view are arms 244 a-b configured to enablemechanical coupling of transducers for EASI of battery 242. Each of arms244 a-b are shown to comprise multiple transducers. Arm 244 a, forexample, is shown to comprise transducers 251 a, 252 a, and 253 a; andarm 244 b is shown to comprise transducers 251 b, 252 b, and 253 b.Corresponding means for applying pressure to each of these transducers251-b, 252 a-b, and 253 a-b are shown as respective springs 246 a-b, 247a-b, and 248 a-b. Although three transducer units are shown to be housedin each arm (e.g., 251 a, 252 a, and 253 a in arm 244 a), thesetransducer units may be individually and independently moveable, eitherwithin their respective arm or they may be housed in separate arms inalternative deployments. Furthermore, the pressures of each transducerunit may be individually controllable (e.g., using springs 246 a, 247 a,and 248 a for transducers 251 a, 252 a, and 253 a, respectively).

FIG. 2C also shows a circuit schematic corresponding to the top view ofholder system 240 discussed above. In an example, transducers 251 a, 252a, and 253 a of arm 244 a may be configured to transmit acoustic signalsand transducers 251 b, 252 b, and 253 b of arm 244 b may be configuredto receive the transmitted acoustic signals (keeping in mind that eachone of transducers 251 b, 252 b, and 253 b may be configured to receiveacoustic signals transmitted from any one or more transducers 251 a, 252a, and 253 a). Wires or interconnects from transducers 251 a-b, 252 a-b,and 253 a-b may be electrically coupled to multiplexor 260, which may,in conjunction with a control block and/or processing element beconfigured to analyze the transmitted and received signals, e.g., forEASI of battery 242.

Furthermore, it is possible to achieve a high quality mechanical contactbetween the above-described transducers and the surface of battery bythe use of acoustic couplants such as, but not limited to, polymer gel,silicone oil, rubber pads, elastomers, epoxy, glycerin, and propyleneglycol, among others. Exemplary battery holders can also be designed toaccommodate holders (e.g., 3D-printed) for strain gauges or othersensors of humidity, chemical species, etc., as well as for componentssuch as thermocouples, or pressure sensors, or for any combination ofsensors.

For example, with reference to FIG. 2D, top and side views of holdersystem 260 are shown with example illustrations for couplants, slots forsensors and slots for thermocouples. In more detail, FIG. 2D showsholder system 260 comprising battery 262 (which may be placed or housedin slot 261, shown in the side view) and arms 264 a-b comprisingtransducers 268 a-b for EASI measurements of battery 262. Further, means266 a-b for applying pressure to respective transducers 268 a-b areshown as any means for constant pressure actuation, e.g., pneumatic,hydraulic, spring, screw, linear actuator, etc. In the side view, anexample wherein means 266 a-b comprises springs 266 a-b, similar toholder systems previously described is shown.

Couplants 272 as shown in the side view may be placed in interfacesbetween battery 262 and transducers 268 a-b to achieve a high qualitymechanical contact between faces of the above-described transducers 268a-b and the surface of battery 262. Couplants 272 may be formed, forexample, from polymer gel, silicone oil, rubber pads, elastomers, epoxy,glycerin, and propylene glycol, among others.

Further, holder system 260 may also include a thermocouple, identifiedwith the reference numeral 270.

In some exemplary aspects, strain measurements and relatedapplications/adjustments thereof may also be performed on exemplarybatteris. For instance, means for measuring strain or other processesfor measuring changes in the thickness of a battery, such as a straingauge, laser distance gauge, infra-red (IR) distance gauge, etc., may beused to measure strain at the transducer-battery interfaces and performany desired adjustments accordingly. Accordingly, one or more slotsidentified with the reference numeral 274 are shown, wherein slots 274may be configured to accommodate the strain gauges or other sensors ofhumidity, pressure, etc., or combinations thereof.

Although the means for applying pressure in holder systems 200, 220,240, and 260 e.g., the springs discussed in FIGS. 2A-D may be suitablein some cases, it is possible for variations to exist between thedifferent means for applying pressure which may be used. Although thesevariations may arise in any means for applying pressure, the case ofsprings will be discussed in further detail to illustrate some of theexemplary features which will be discussed in the following section. Inthe case of springs, variations may arise during their manufacture.Variations may also exist in spring constant, stiffness, etc., betweendifferent springs. These variations in characteristics of the springsmay give rise to variations in the pressure applied by the spring,between the respective transducers and the battery to which thetransducers are mechanically coupled to, wherein the pressure isreferred to herein as “P_(td)”. Furthermore, over the course ofcharge/discharge cycles of a battery, and with age, the volume of thebattery may expand, which can lead to additional compression of springsused in applying pressure to the transducers, thus leading to potentialchanges in P_(td) as well. EASI is understood to be dependent on P_(td),which means that changes in P_(td) such as the above-noted increase inP_(td) can affect the measured acoustic signal. It is thereforedesirable to maintain a constant pressure P_(td) at thetransducer-battery interface for the case of springs and more generallyfor the case of any device or means for applying pressure on thetransducers. Accordingly, the following sections describe devices ormeans for adjusting the pressure applied by the devices or means forapplying the pressure.

FIGS. 3A-D show several example holder systems configured for adjustablepressure P_(td) at transducer-battery interfaces, e.g., for EASI. FIG.3A illustrates an example holder system 300 similar to holder system 200discussed in FIG. 2A, without additional arrangements configured foradjustable pressure P_(td). In more detail, holder system 300 comprisesbattery 302, with arms 304 a-b configured to hold transducers 308 a-bmechanically coupled to battery 302, and with respective springs 306 a-bconfigured to apply pressure on transducers 308 a-b to facilitate thecoupling.

FIG. 3B shows holder system 310 which comprises an enhancement to holdersystem 300 of FIG. 3A, wherein holder system 310 comprises one or morepressure adjusting devices, shown in this case as plates or slots 314configured to couple transducers 308 a-b to battery 302, whereinpressure may be adjusted using screws/bolts 312 (e.g., lead screws). Inthis implementation, the pressure adjusting device or means foradjusting pressure on the interface between battery 302 and transducers308 a-b is disposed at the interface. Pressure sensors (not shown) maybe placed at the interface between battery 302 and each of transducers308 a-b, e.g., to measure P_(td) at the time of assembly and thenapplying or maintaining the constant pressure at the transducer-batteryinterfaces.

As an alternative to the above-described plates 314 and screws/bolts 312configured as means for adjusting pressure, it is also possible to usemotorized linear actuators, linear stepper motors, motorized lead screw,or other computer-controlled actuators to apply adjustable pressure anduse the pressure sensors as part of a feedback loop to ensure properpressure levels are met and/or maintained. Such designs that utilize apressure sensor, either with the manual lead screw or with thecomputer-controlled actuators, can also be used to monitor and maintainP_(td) during the course of charge/discharge cycling of the battery.

FIG. 3C shows holder system 320 configured with another exemplary meansfor adjusting the pressure applied on the transducer-battery interfaces.In this case, the pressure of the means for applying pressure ontransducers 308 a-b, e.g., springs 306 a-b, may be adjusted with meansfor adjusting the pressure such as screws/bolts 322 a-b respectively,which may be provided within or in conjunction with corresponding arms304 a-b. In similar manner as discussed with reference to FIG. 3B,alternative means for adjusting pressure can include motorized linearactuators, linear stepper motors, motorized lead screw, or othercomputer-controlled actuators to apply adjustable pressure. Pressuresensors may once again be provided at the transducer-battery interfacesor alternatively, may be provided at the interfaces between screws 322a-b and respective transducers 308 a-b, wherein the pressure sensors maybe used as part of a feedback loop to ensure proper pressure levels aremet and/or maintained at the transducer-battery interfaces.

FIG. 3D shows another exemplary holder system 330, wherein the means forapplying pressure and the means for adjusting the pressure may becombined into the same mechanism. In this case, springs 306 a-b shown inFIGS. 3A-C are omitted and screws 332 a-b are shown as being configuredto directly apply and adjust pressure on transducers 308 a-b. Aspreviously mentioned, alternative mechanisms may be used instead of orin conjunction with screws 332 a-b for the purposes of applying andmaintaining constant pressure on battery 302 over the course of variousmeasurements for EASI-based analysis.

FIG. 3E shows another exemplary holder system 340, wherein a puck isplaced between the means for adjusting or applying pressure (or pressureactuation mechanism) and the back of a respective transducer. Forinstance, pucks 344 a-b are placed between any means for actuation ormeans for applying/adjusting pressure 342 a-b and respective backs oftransducers 308 a-b. Couplants 346 are shown between faces or fronts oftransducers 308 a-b and battery 302 as an optional feature for holdersystem 340.

Pucks 344 a-b are configured to maintain contact with the flat backsurfaces of the respective transducers 308 a-b, thus distributing thepressure applied across the faces of transducers 308 a-b. Various viewsincluding front, side, and back views of an example puck 342 a/b havebeen illustrated. As seen from the back view, puck 342 a/b has a slot inthe back to accommodate a piston or spring or “arm” of the pressureactuator or respective means for applying/adjusting pressure 342 a/b.Additionally, puck 342 a/b may nominally be of the same radialdimensions as the respective transducer 308 a/b and slide in atransducer holder groove smoothly. As shown in the expanded view, puck342 a/b may have appendage 347 (e.g., comprising a ring or circularclamp as seen in the front and side views of puck 342 a/b) configured tofit around cable fixture 348 attached to the respective transducer 308a/b. Puck 342 a/b may also be designed to nestle or house at least aback portion of the respective transducer 308 a/b within it. In theabove-described aspects, pucks 344 a-b may improve alignment ofrespective transducers 308 a-b with battery 342 and also for improvedrepeatability/consistency of the acoustic signals transmitted/receivedby respective transducers 308 a-b.

In some aspects, maintaining a constant stack pressure on the batterywhich is invariant with the initial thickness of the battery or anychanges in battery thickness during charge/discharge cycling, exemplaryholder systems are disclosed herein which may be gravity-assisted.

With reference to FIG. 4, another gravity-assisted holder system 400 isshown, wherein battery 402 is placed onto a platform, wherein theplatform may comprise a fixed base 418 (e.g., constructed with a 3Dprinter in a low-cost and flexible implementation) with a top surfaceformed by a metal block or metal plate 412 a, for example. The slotwhere battery 402 may be placed on top of metal plate 412 a has beenshown.

Depending on the type of battery or geometry of the battery, anothermetal block or metal plate 412 b may be configured to make contact withthe battery on a surface different from, or more specifically, oppositeto that of metal plate 412 a. In this case, in a side-view asillustrated, with the platform comprising fixed base 418 and metal plate412 a on the bottom side of battery 402, metal plate 412 b may beconfigured to make contact with the top side of battery 402. Further,metal plate 412 b may be moveable, by means of lubricated metal posts414 passing through pre-made holes in metal plate 412 b (oralternatively, other means for providing free motion to metal blocks 412b such as rails, rods, tracks, etc.). Corresponding holes may also bemade in metal plate 412 a and fixed base 418 to accommodate anyremaining length of metal posts 414. Alternatively, bottom and top metalplates 414 a-b may have grooves machine-cut to fit any geometry ofbattery 402, including rectangular slots for pouch and prismatic cellsand semicircular segments for cylindrical cells. By this arrangement,metal plate 412 b may be configured to provide a constant pressure onbattery 402, assisted by gravity.

Although additional means for applying pressure may be dispensed with,in the illustrated implementation, arms 404 a-b are shown to be attachedto or mechanically coupled to metal plates 414 a-b respectively, witharms 404 a-b respectively comprising transducers 408 a-b and additionalmeans for applying pressure such as springs 406 a-b. In combination,holder system 400 may be configured to electrically and/or mechanicallycouple transducers 408 a-b for transmitting/receiving acoustic signalsinto/from battery 402 for EASI of battery 402.

Although metal plates 412 a-b or metal blocks have been discussed above,any means for applying a constant mass on top of a battery situated on afixed base or platform may be used instead. In the illustrated exampleof holder system 400, metal block 412 b, to which transducer 408 b isaffixed, may be configured to move freely along metal posts 414. Withthis configuration, as battery 402 goes through charge/discharge cycles,for example, corresponding, the constant mass comprising arm 404 b maymove along metal posts 414 and a constant applied pressure may bemaintained on the transducer-battery interfaces in this manner.

Additionally, pressure sensors can be placed between transducers 408 a-band respective metal plates 412 a-b and means for adjusting pressuresuch as screws 410 a-b are also illustrated aspect. As alternative meansfor adjusting pressure, computer-controlled actuators, pneumatic orelectromagnetic solenoids, linear or other types of mechanicalactuators, etc., may be used to apply a constant P_(td) on metal plates412 a-b. By utilizing a strain gauge or other means for measuringchanges in the thickness of battery 402, an additional measurement ofthe precise battery thickness during charge/discharge cycling, forexample, can be obtained. This thickness measurement can be automated invarious ways, for example with displacement sensors placed along posts414 and connected to a computer.

Exemplary holder systems discussed herein may be of a modular design.For example, the aspects of the holders used to house the transducerunits (referred to as “arms” above), and the aspects of the holderswhich accommodate the battery (or “battery holders”) can be independentfrom each other, or can be coupled as needed. The aspects of the holdersfor accommodating the battery can comprise flexible units (e.g., 3Dprinted), metal, or plastic jackets with identical and in someinstances, coaxial slots to expose the body or surface of the battery tothe transducers. In some aspects, the slots need not be coaxial and maysupport arrangements of transducers wherein off-axis transducermeasurements may be performed.

The arms may have a fixture that fits onto the battery holders such thatthe transducers sit precisely on the surface of the battery through theslots on the battery holder.

Further, the battery holder can also be designed to accommodate holders(e.g., 3D-printed) for strain gauges or other sensors of humidity,chemical species, etc., as well as for components such as thermocouples,or pressure sensors, or for any combination of sensors.

The battery holders and sensor holders may also have universal fixturesthat enable the various sensor holders to be precisely affixed to thebattery holder. The universal fixtures enable measurements on the bodyof the batteries to be taken through slots in the battery holder. Thesensor holders can be pre-loaded and attached to the battery holdersprior to placing the batteries within the battery holders according todisclosed aspects.

The above-described modular designs for holder systems may be configuredfor collecting long term charge/discharge cycling data as well as formeasuring temperature, pressure, and internal structure of the batteriesthrough acoustic signal based analyses such as EASI. The exemplarymodular holder systems may also be advantageously configured for quick,short-term measurements of open circuit voltage, temperature, internalpressure, and internal structure using EASI. The measurement of multiplephysical parameters in one “snapshot” allows battery tests to beperformed, for example, to check whether all parameters are withintolerance levels and ready for use.

The exemplary holder designs described above may be configured formanual setup/loading of individual batteries and where applicable,sensors, into the holder systems. However, manual loading can causeuser-related inefficiencies and errors. If the EASI is performed on abattery manufacturing line, for example, high throughput operation maybe achieved by automating the loading and setup processes. In suchautomated deployments, for example, the sensor holders may be moreadvantageously designed into a battery holder in advance, and thebattery holders may be designed into automated actuator arms or unitsthat can be efficiently and rapidly placed onto each battery under testfor high-throughput measurements. The battery holders can be attached tomechanical arms which have motion and pressure sensors to detect thepresence of a battery in its path and automatically close or lock inplace the battery holder and complete the measurements. Suchimplementations of automated battery alignment with battery holders maybe used to ensure that the pressure applied by the transducers (forEASI) and strain gauge or other techniques for measuring batterythickness, for example, are accurate as related settings can beprogrammed into the automated mechanical arms.

FIG. 5 illustrates representative aspects of an exemplary automatedholder system. More specifically, a side view and a top view a holdersuch as holder 400 of FIG. 4 are shown. The side view illustratesconstant pressure actuators or means for adjusting pressure such asscrews 410 a-b, transducer holders such as metal plates 412 a-b (withmovable holder or top metal plate 412 b and fixed holder or bottom metalplate 412 a) comprising slots for sensors, as well as transducers 408a-b (which may include arrays of transducers in some aspects). The topview illustrates top metal plate 412 b, arm 404 b, and screw 410 b. Inan example implementation, the illustrated top portions of holder system400 (e.g., arm 404 b and metal plate 412 b) may be moveable, e.g., usingan automated system configured to raise and lower these top portions tomechanically couple related transducers to each battery as it passesthrough holder system 400. Various batteries 502 a, b, c, d, e areshown, with battery 502 c is precisely aligned under the top portion ofholder system 400. The batteries 502 a-e may be placed on conveyor belt504, e.g., akin to a production line, and as conveyor belt 504 passesthe batteries 502 a-e through the sensor unit, physical measurements canbe quickly taken.

Exemplary automated measurement systems such as the one depicted in FIG.5 can be incorporated into a systems for quality control/qualityassurance, wherein the outputs of the measurement sensors may be fedinto an algorithm used for grading/rating the quality of the batteriestested and to sort or bin the batteries accordingly.

In conventional designs for battery testing, separate platform designsmay be required for different geometries such as rectangular,cylindrical, etc. However, exemplary holder systems may be configured asuniversal holder systems in the sense that they may adapt to oraccommodate any geometry or shape of the batteries under test. In someaspects, the exemplary universal holder systems may incorporatemechanical actuation into the battery holder for securing andpositioning the battery under test. For example, one or more optical orhaptic or other type of proximity sensors may be used to gauge the shapeand location of a battery within the battery holder during placement ofthe battery into the battery holder. Further, computer-controlledmechanisms may then be used to actuate mechanical parts to properlyplace, align, and secure the battery for measurement. A similar type ofsensor holder with universal fixtures, as described herein, may also beused to enable modular sensor designs.

In some aspects, a fluid couplant such as polymer gel, silicone oil,glycerin, propylene glycol, or combinations thereof may be used toensure proper mechanical coupling between the acoustic transducers andobjects they may be used to test, e.g., the batteries in above-describedaspects. The fluid couplant may create or improve mechanical contact.However, in some instances, the fluid couplant may flow or drain awayfrom the interface between the transducer (or arm holding the transducer(and battery under test, so the fluid couplant may not last for multiplemeasurements. The fluid couplant may be particularly short-lived orunsuitable in in high throughput environments like a battery productionline.

Accordingly, in some aspects of this disclosure, a non-fluid couplantmay be used instead, wherein the non-fluid couplant may be applied tothe transducer (or arm holding the transducer). The non-fluid couplantapplied in this manner may reliably improve mechanical contact betweenthe transducer and the battery under test for multiple measurementswithout causing damage to the battery or leaving any residue behind.

With reference now to FIG. 6, holder system 600 is shown, whichcomprises several features of holder system 240 described previouslywith reference to FIG. 2C and an exhaustive repetition of like-numberedcomponents will be avoided. Briefly, as seen, FIG. 6 shows a schematicview of a circuit with transducers 251 a, 252 a, and 253 a of arm 244 aconfigured, for example, to transmit acoustic signals and transducers251 b, 252 b, and 253 b of arm 244 b configured, for example, to receivethe transmitted acoustic signals (keeping in mind that each one oftransducers 251 b, 252 b, and 253 b may be configured to receiveacoustic signals transmitted from any one or more transducers 251 a, 252a, and 253 a). Wires or interconnects from transducers 251 a-b, 252 a-b,and 253 a-b may be electrically coupled to multiplexor 260. Ultrasonicpulser/receiver 604 may be configured to transmit signals to multiplexor260 for proper routing to the appropriate transducers 251 a, 252 a, and253 a for transmission and correspondingly, multiplexor 260 may routethe received signals from transducers 251 b, 252 b, and 253 b back toultrasonic pulser/receiver 604 for further analysis (wherein, it will beunderstood that in some implementations, the pulser and receiverportions of ultrasonic pulser/receiver 604 may be contained within asingle unit, while in other implementations, the pulser and receiverportions may be separately housed and/or separately controlled).Computer 602 coupled to ultrasonic pulser/receiver 604 may aid in theanalysis, e.g., by performing calculations pertaining to EASI of battery242.

Also shown in FIG. 6 are couplants between transducers 251 a-b, 252 a-b,253 a-b and battery 242. Couplants between respective transducers andthe body of battery 242 have been identified with the reference numeral606. Couplants 606 may be fluid or non-fluid couplants. In one aspect,couplants 606 may be configured as non-fluid or dry couplants asdiscussed above and applied at the respective interfaces shown formaintaining good mechanical contact between the respective transducersand the body of battery 242 over numerous tests. Dry couplants such ascouplants 606 may be applied in the shape of a boot or cover torespective transducers (or arms housing the transducers) or othersensors. Several types of dry couplants may be utilized for formingcouplants 606, including, for example, silicone rubber, elastomers,waxes, cyanoacrylates, epoxies, etc. These dry couplants may be appliedonto the transducers (e.g., in the shape of a boot or cover) and fixedto the battery holder, e.g., to arms 244 a-b. The battery holder canalso be designed with a mechanical ultrasound couplant transducer bootin some instances.

In exemplary aspects, it is recognized that the transducers provided inexample holder systems may not be acoustic point sources, but rather,may have finite diameters, wherein the acoustic waves transmitted by atransducer, for example, may emanate from the entire surface of thetransducer (e.g., implemented as a piezoelectric transducer (PZT) orPolyvinilidene fluoride (PVDF) transducer, etc.). A transducer whoseface is a planar round shape is observed to emit a sound field thatresembles a cylindrical mass in front of the transducer. As the acousticwave originates from a number of points along the transducer's face, theintensity of the ultrasound signal emitted, along the beam is affectedby constructive and destructive wave interference, also known asdiffraction. These types of interferences may lead to extensivefluctuations in the intensity of the ultrasound signal near the source,i.e., the transducer, which is referred to as a “near field” of thetransducer. Because of acoustic variations within the near field,accurate evaluation of flaws in materials (e.g., batteries) when theyare positioned within the near field is challenging.

The area beyond the near field, wherein the ultrasonic wave is moreuniform is referred to as a “far field” of the transducer. In the farfield, the ultrasonic wave is observed to spread out in a patternoriginating from the center of the face of the transducer. Thetransition between the near field and the far field occurs at adistance, N, and is sometimes referred to as a “natural focus” of a flat(or unfocused) transducer. The near/far field distance, N, issignificant because amplitude variations that characterize the nearfield change to a smoothly-declining amplitude at the point oftransition. An area immediately beyond the near field, with respect tothe transducer, is observed to be the area wherein the ultrasonic waveis well-behaved and at its maximum strength. Therefore, optimaldetection results may be obtained when the sample or battery test isplaced at a distance slightly beyond distance N from the face of thetransducer. In exemplary aspects, a waveguide may be deployed toposition the sample or the battery just beyond the “near field” of thetransducer.

With reference to FIG. 7, a top view of holder system 700 is shown withbattery 702 and arms 704 a-b comprising transducers 708 a-b for EASImeasurements, pucks 714 a-b (as described with reference to FIG. 3E),and means for applying/adjusting pressure 712 a-b, respectively. In anexample, transducer 708 b may be configured as a transmission transducerfor emitting ultrasonic waves and transducer 708 a may be configured asa receiver transducer. Also shown is waveguide 720, disposed betweentransducer 708 b and battery 702, configured to position battery 702beyond the near field of transducer 708 b. The distance N wherewaveguide 720 causes battery 702 to be positioned with respect totransducer 708 b may be calculated as follows: N=D²ƒ/4c, wherein D is adiameter of transducer 708 b, ƒ is a frequency of the acoustic orultrasonic wave transmitted by transducer 708 b, and c is the speed ofsound in the medium or material of waveguide 720.

Waveguide 720 may be implemented as a cylinder or block of length N anddiameter D and of a known material (wherein, c is the speed of sound inthe known material) and placed in front of the transmitting transducer708 b of frequency ƒ, to position battery 702 just beyond the “nearfield” of transducer 708 b. Implementations wherein the waveguide ismade of a material with very low attenuation are seen to be advantageousin exemplary aspects. Additionally, couplants (as discussed withreference to FIG. 2D, 6) may be used to improve the mechanical contactbetween the various components of holder system 700. For example,couplant 716 a may be disposed between waveguide 720 and battery 702 and716 b between transducer 708 b and waveguide 720 as shown.

Waveguide 720 may be included as a part of holder system 700 accordingto FIG. 7 to improve the quality of the acoustic signals that enterbattery 702, and are received at the receiver transducer 708 a on theother side of battery 702. With the use of waveguide 720, the “nearfield” fluctuations in the acoustic wave can be avoided or minimized andthe acoustic measurement reliability may be correspondingly improved.

It will be appreciated that aspects include various methods forperforming the processes, functions and/or algorithms disclosed herein.For example, FIG. 8 illustrates an exemplary method 800 of testing abattery (e.g., battery 202 of FIG. 2A).

Block 802 comprises coupling one or more transducers to the battery(e.g., transducers 208 a-b), the one or more transducers configured forelectrochemical-acoustic signal interrogation (EASI) of the battery.

Block 84 comprises coupling the at least one arm to the battery, whereinat least one transducer is housed in the at least one arm (e.g., arms204 a-b)

Block 806 comprises applying pressure (e.g., using pressure applyingdevices such as springs 206 a-b) to the at least one transducer, tocontrol pressure between the at least one transducer and the battery.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the aspects disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The methods, sequences and/or algorithms described in connection withthe aspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium.

Accordingly, an aspect of the invention can include a computer-readablemedia embodying a method for analyzing a battery using transducerscoupled to the battery, for transmitting/receiving acoustic signals.Accordingly, the invention is not limited to illustrated examples andany means for performing the functionality described herein are includedin aspects of the invention.

While the foregoing disclosure shows illustrative aspects of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the aspects of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. An apparatus comprising: a holder systemconfigured to couple one or more transducers to a battery, the one ormore transducers configured for electrochemical-acoustic signalinterrogation (EASI) of the battery, the holder system comprising: atleast one arm configured to house at least one transducer to be coupledto the battery; and a pressure applying device configured to applypressure to the at least one transducer, to control pressure between theat least one transducer and the battery.
 2. The apparatus of claim 1,wherein the at least one transducer is one of a transmitter or receiverof acoustic signals.
 3. The apparatus of claim 2 further comprising anultrasonic pulser and receiver, configured to transmit an acoustic pulsethrough a first transducer configured to transmit acoustic signals andreceive the transmitted pulse through a second transducer configured toreceive acoustic signals.
 4. The apparatus of claim 3 wherein the firsttransducer is housed in a first arm and the second transducer is housedin a second arm, wherein the first arm and the second arm areindependently moveable, and wherein the first arm and the second arm aredisposed to be one of: coaxial or off-axis with respect to each other.5. The apparatus of claim 3 wherein the first transducer and the secondtransducer are housed in a first arm.
 6. The apparatus of claim 1,wherein the pressure applying device comprises one or more of springs,pneumatic pressure mechanisms, lead screws, linear actuators, orelectromagnetic solenoids.
 7. The apparatus of claim 1, furthercomprising a pressure adjusting device configured to adjust the pressureapplied by the pressure applying device.
 8. The apparatus of claim 7,wherein the pressure adjusting device comprises one or more of: a screwand bolt assembly disposed at an interface between the at least onetransducer and the battery; or a screw disposed at an outer side of theat least one transducer, the outer side opposite to the interfacebetween the at least one transducer and the battery.
 9. The apparatus ofclaim 7, further comprising at least one pressure sensor configured todetermine pressure between the at least one transducer and the battery,wherein the pressure adjusting device comprises one or more motorizedlinear actuators, linear stepper motors, motorized lead screws,computer-controlled actuators configured to apply adjustable pressurebased on feedback from the at least one pressure sensor,computer-controlled pneumatic valves, computer-controlled pistons, orcomputer-controlled solenoids.
 10. The apparatus of claim 1, furthercomprising a strain gauge configured to determine strain at an interfacebetween the at least one transducer and the battery.
 11. The apparatusof claim 1, wherein the pressure applying device comprises agravity-assisted device comprising a fixed platform and a moveableplatform, the moveable platform configured to apply pressure based ongravity, with the at least one arm coupled to the moveable platform. 12.The apparatus of claim 1, wherein the battery comprises cells of one ormore geometries including a pouch cell or a cylindrical cell.
 13. Theapparatus of claim 1, wherein the holder system further comprises one ormore of a slot to accommodate the battery, a slot to accommodate thebattery, or one or more slots to accommodate one or more sensors. 14.The apparatus of claim 1, further comprising a device for automatic,robotic, or computer-controlled placement of the arm with respect to thebattery for precise alignment of the at least one transducer.
 15. Theapparatus of claim 14, wherein the device comprises a conveyor beltconfigured to bring two or more batteries into contact with the at leastone arm in a stepwise manner during a process of testing the two or morebatteries.
 16. The apparatus of claim 1, further comprising a non-fluidcouplant applied to the at least one transducer to improve mechanicalcontact between the at least one transducer and the battery.
 17. Theapparatus of claim 1, further comprising a puck configured to maintaincontact with a back surface of the at least one transducer and todistribute pressure at an interface between the at least one transducerand the battery.
 18. The apparatus of claim 17, wherein the puckcomprises a slot to accommodate a piston of the pressure applyingdevice.
 19. The apparatus of claim 17, wherein the puck is configured tohouse at least a back portion of the at least one transducer or whereinthe puck comprises an appendage configured to fit around a cable fixtureattached to the at least one transducer.
 20. The apparatus of claim 1,further comprising a waveguide disposed between the battery and the atleast one transducer, wherein the waveguide is configured to positionthe battery beyond a near field of the at least one transducer.
 21. Theapparatus of claim 20, wherein the waveguide is a cylinder of length Nand diameter D, with a speed of sound through the waveguide is c, andthe at least one transducer is configured to transmit acoustic signalsat a frequency ƒ, and wherein N=D²ƒ/4c.
 22. A method of testing abattery, the method comprising: coupling one or more transducers to thebattery, the one or more transducers configured forelectrochemical-acoustic signal interrogation (EASI) of the battery;coupling the at least one arm to the battery, wherein at least onetransducer is housed in the at least one arm; and applying pressure tothe at least one transducer, to control pressure between the at leastone transducer and the battery.
 23. The method of claim 22, furthercomprising determining the pressure between the at least one transducerand the battery and adjusting the pressure applied to the at least onetransducer based on the determined pressure.
 24. The method of claim 22,further comprising precisely aligning the arm with respect to thebattery based on automatic, robotic, or computer-controlled mechanisms.25. The method of claim 24, comprising placing two or more batteries ona conveyor belt and bringing the two or more batteries into contact withthe at least one arm in a stepwise manner.
 26. The method of claim 22,further comprising applying a couplant to the at least one transducer toimprove mechanical contact between the at least one transducer and thebattery.
 27. The method of claim 22, further distributing pressure at aninterface between the at least one transducer and the battery based onconfiguring a puck in contact with a back surface of the at least onetransducer.
 28. The method of claim 22, further comprising disposing awaveguide between the battery and the at least one transducer forpositioning the battery beyond a near field of the at least onetransducer.
 29. A battery holder system comprising: means for housing atleast one transducer to be coupled to a battery under test, the at leastone transducers configured for electrochemical-acoustic signalinterrogation (EASI) of the battery; and means for applying pressure tothe at least one transducer for controlling pressure between the atleast one transducer and the battery.
 30. The battery holder system ofclaim 29, further comprising means for determining the pressure betweenthe at least one transducer and the battery and means for adjusting thepressure applied to the at least one transducer based on the determinedpressure.